[5178.]-PLENUM PNEUMATIC (U. Q.).—The following is a brief statement of the condition of the work upon the bridge of St. Louis, according to the latest advice from its constructor, James B. Eads, C.E.:-"The masonry of the west abutment is about 14ft. above the present stage of the river. The western pier is about The laying of the masonry is progressing on the west abutment and on the cast pier. The granite (from Portland, Maine) for the west pier is on its way up the river. Some fifty or sixty vessels, laden with granite for the works, are now upon the ocean, and two cargoes on their way up the Mississippi from New Orleans; no further delay is therefore anticipated on account of material for masonry. The caisson for the eastern abutment is nearly finished at Carondolet, six miles below the city, and will be launched and placed in position in about two weeks. This abutment will be sunk to the bed-rock, 126ft. below extreme high water-mark, and will consequently penetrate eight feet deeper than the pier which was put down last winter. These four masses of masonry constitute the foundations for the bridge proper. Those for three of the smaller piers on the western approach have already been put in, the deepest one extending 21ft. below the city directrix. This one has been recently put down, and is nearly completed to the wharf level."-From the Scientific American, Dec. 20,

16ft. and the eastern pier about four feet above water.

1870.-SERGIUS.

[5292.]-PERCUSSION ACTION FOR HARMONIUM. -I observe "J. C. L.'s" reply to query. I had a percussion action harmonium some years ago, and it had a set of hammers which struck the tongues of the reeds on touching the keys, so that even without wind I had a slight sound from the instrument, quite sufficient as a guide to fingering. My expression stop had no control over the percussion action whatever. "J. C. L." is surely in error to say "the percussion action ( alias expression stop)."-A MERE NOVICE.

[5292.] PERCUSSION ACTION FOR HARMONIUM.-J. C. L." has very little idea of the percussion action of the harmonium when he says "alias expression stop." He describes the expression stop correctly, but the percussion action is a set of hammers, similar to piano-hammers, placed under one row of reeds, which, striking the said reeds, produce instant vibra

tion.-J. D.

[5532.]-A WRECK (U.Q.).-Let " Old Trawler" hunt up some old boiler shells, and with a very little trouble'and expense he can get them converted into pontoons and dams to work in. There are plenty such lying about the country. They can be sold afterwards with the cargo for old iron.-JACK OF ALL TRADES,

(5547.] SHEEPSKINS FOR ORGAN BELLOWS (U.Q.). See answer to sheepskins, 5661. See treatment after in 4754, dressing of skins, but dispense with the galls or tan liquor for white leather. The strained and unstrained should be both strained to a certain extent. The strained, so called, to be strained when damp, and dressed with whiting and alum; the whole strained. The other, called unstrained, served the same, but not dressed, but taken down and broken upon the flesh side with the pumice ball and sand until soft.-JACK OF ALL

TRADES.

[5551.]-MALLEABLE CAST-IRON (U.Q.). Let "G. R. H." use equal parts of best Welsh, ditto Scotch, ditto hematite, and use fine chalk or lime to anneal them in. I have used the two first, and have made it in. thick in three days, so that I could bend and hammer it to a great extent without breaking. Could I have got the hematite I should have tried further experiments. -JACK OF ALL TRADES.

with the pins upon the barrel he wishes to do away with
I expect. I have put washers in different parts of them
a metal box with glass tops instead of horn-which has
for the same purpose-those that have been inclosed in
greatly improved them.-JACK OF ALL TRAdes.
(5615.]-MUSICAL BOX (U. Q.).-The jarring of
musical box when playing is often caused by particles
of dust getting in between the teeth of comb and be-
tween the lead of bass notes. Take the comb off and
clean it well with piece of soft paper between tongues,
ard if it really touches the barrel, pack it with a strip
of paper before screwing on. I think this will answer;
it would be a risk to bend tongues, besides looking bad.
-OLD CLOCK JOBBER.

[5620.] CLOCK CHAINS (U. Q.).-What is it you
want, a S hook chain or oval link? If the first, wind
Your wire around a round steel or iron rod; part every
other link and twist, linking one in the other. If oval,
get a rod and flatten the size you want it, file it the shape
you require, wind the wire, cut with a sharp chisel right
down the centre of one side the ellipse, draw them off and
link up.-JACK OF ALL TRADES.

[5620.]-CLOCK CHAINS (U. Q.)-I make my clock chains as follows:-Get a short rod of iron or hard wood, file it oval so that a link of the old chain will slide easily by wrapping wire round it close until full, take off and on about 4in., it will then be the right size; then begin separate links with nippers, join them and close with pliers: repeat until chain is long enough. "J. B." will find this simple, and may easily make his chain in an hour.-OLD CLOCK JOBBER.

[5647.)-RULE WANTED.-FORCE OF IMPACT.

Has Mr. Roe not read the account given by Brewster of
the tallow candle that went through the 2in. deal?
Yet how difficult it would be to squeeze it through a
cake of tallow not so thick.-M. P.

[5862.]-GROVE'S BATTERY.-"M." should try a piece of patent plate-glass, with ground edges, a little to support his thin sheet of platinum. A quarter inc smaller than his porous cell in width, and a little longer, of platinum bent over the top of the glass will support the sheet, and afford an easy method of connecting the strips of zinc.-S. L. T.

[5935.]-LANDSCAPE LENS FOR TELESCOPE.-I may tell" Jabez "that I have used a plate photograp lens for an astronomical telescope, and it acts admi ably; it will show Jupiter's satellites with a power of 10 only. Its diameter is 1in.-ROBINSON CRUSOE.

[5954.]-SAFETY VALVE.-I have had some ex perience in safety valves and pressure gauges, secur since the invention of Bourdon's steam and vacan gauges, I have had some hundreds pass through my hands; have had hydraulic apparatus to make to te and adjust them and safety valves, &c. I will give yea a little that I have proved :-1st. That you cannot get a conical seated valve to answer to the same pressure twice alike. 2nd. A flat seated valve is most accurate. 3rd. I have tested gauges (Bourdon's) after severe work apen the bri-y ocean from 3 to 5 years, subject to the asrosive action of salt water, and have found them, if prNow, a word upon fixing. The Bourdon gauge ought perly fixed and adjusted, as true as they were when bes never to be fixed direct up the boiler, or the dome one, by a short pipe, but by an inverted siphon tabe the higher the pressure the longer the tube. I have had them come into my hands choked with scum from the water, both fresh and salt, and many choked with red lead being put in to make the conical union junetka supplied with them and the junction with the cock likewise supplied. In the conical junction and union there is nothing required in the junction with the cock but s grumet of hemp saturated with tallow or beesyaL A sketch will illustrate the method of fixing. I have sen a Bourdon that has been fixed 12 or 14 years as good as as it was the day it was put up; that was upon a th copper pipe inverted siphon descending 10ft. from the top of boiler, the after leg extending 10ft. above the boiler upon which stood the gauge, after the sketch. a is a screw for probing in case it should become

[5647.)-RULE WANTED.-FORCE OF IMPACT.-
My query has raised a controversy which has benefited
myself, and perhaps some other subscribers, and if so,
I hope none will enter into the "solemn league and
covenant" proposed in "E. L. G.'s" letter of December
30th. Rather take the advice of J. G. Grenfell, in letter
1140, and think twice before answering queries in such a
manner as Mr. Barwick answered nine. Two corre-
spondents have shown his mistake, and J. G. Grenfell choked. But that is not
may well say it is difficult to over-estimate the value of the most essential part
these pages of answers to many a worker struggling on
of it, it is principally for
alone, and equally difficult to over-estimate the harm a charge of fresh water,
done by ignorant persons presuming to answer questions when all things are fixed.
on subjects of which they know nothing. The answer of previous to getting up
"J. B." caused me considerable trouble. "E. L. G." steam. I was aware of
cannot conceive such querists who ask questions like the irregular action of
mine reading any other queries with the least intent of the conical-seated safety
answering them. When I sent my query it was with the valve some years ago,
intention of learning something, and with it I sent re-
and in 1845 or 1846 pro.
plies to two other queries, and if "E. L. G." will look a posed a form of piston
queries above my name and late nom de plume of "One." by which the pressure
few back numbers over he will find I have answered indicator safety valve,
A discussion I care nothing about, having no time to you had in your boiler
the thousands of "working mechanics" in this country any time.
spare; for one, I wish to learn what I can, and if ont of could be ascertained at
After sub-
(of which body I am one, doing my 104 hours per day) amitting it to one, whom
few could be persuaded to read and answer queries in I supposed to be a friend
the, or "our," MECHANIC, many a one struggling on alone
would be benefited. I cannot persuade one among my
numerous acquaintances (mechanics) to take in the
MECHANIC: they say it is a good paper, but above their
understanding, and little in it to benefit the practical
man; it is more a scientific paper than one suited to the
wants of workmen. I tried to get subscribers in the
hope of seeing something added to the MECHANIC in
the shape of enlarging it to take in reports of mechanical
institutions and drawings of machinery, which would
bear out its name of ENGLISH MECHANIC. There are
but few mechanics who care about building organs (I
am writing from experience, as did the subscriber who
said the working man cares more for his pipe and beer),
though such details are interesting. But the time for
more mechanical matter waits till many more names are
added as subscribers to "our" MECHANIC. My query
has been answered in a manner I perfectly understand
by C. W. Stidstone, J. B. Primus, and "E. L. G." If the
answers which J. G. Grenfell calls "rubbish shot into
other readers who send the answers (that is those
these columns") will, if they can, make their meaning
clearer, I shall be much obliged.-W. FRED. ROE.
[5753.1-OLD CORK CUTTINGS may be profitably
employed in making life buoys.-C. M.

[5768.]-POISONED WHEAT.-I know not Barber's
wheat; but during some years on a farm we used crowfig,
[5560.]-HUMOURS OF THE EYE.-Do not all eyes,
as a means of destroying the vermin, prepared thus:
or the same eyes, at different periods of life differ?-
The crowfig was simmered in water some time, and after
M. P.
wards put the wheat in to allow it to soak and swell,
[5569.]-GREENHOUSE STEPPERS (U.Q.).—I send and then threw it about the farm; not hurtful to animals.

LA

an illustration of this useful article in two positions, which I hope will be sufficient for the querist. By turning the back of the chair over to the front, the steps are formed. Elm is a good wood of which to make them.S. R.

[5571.]-SCREW ENGINE (U.Q.).-Cylinder: diameter, 4iu.; stroke, 7in.; the area parts = area of piston, which is necessary for the quick action; not forgetting plenty of room on the exhaust.-JACK OF ALL TRADES. [5604.]-FIXING SMALL WHEEL TO MANDREL (U.Q.). Take a pattern from Whitworth's. Let the mandrel project, and make the wheels slip off and on with a key-way cut in them, and a feather put in the mandrel to keep them from twisting.-JACK OF ALL TRADES.

[5615.]-MUSICAL BOX (U.Q.).-Let "R. O. R." try a strip of oil silk between comb and foundation. It is the unmusical metallic click of the comb coming in contact

--W. DARNELL.

[5774.]-THE MAGNETIC POLES.-The phenomena known as magnetism are the result of etherial eddies. These are the same in origin and character as those we notice in the stream or water brook. The cause of an etherial eddy is the conduction of a thread of the earth current by the metal (magnet). By conduction must be understood acceleration. As these fine threads or veins cannot travel faster than the main current where there is no accelerator (magnet) at hand, they eddy back to the point from which they acquired acceleration-the opposite end or pole from which they issued. The earth current is always flowing, and the metal is always conducting (accelerating) such part of it as comes within its range. The keyhole and the draught is a homely instance of this to some extent. An eddy is the inevitable consequence of the part of a current turning back because it cannot go forward, ard a direct motion (movement) being converted into a circular one. This is demonstrated and placed beyond cavil, and magnetism is no longer a mystery.-OMEGA.

[5844.]-BOILER EXPLOSIONS.-I beg to inform Fred. Roe, pp. 263, 323, 333, that I meant an underfired non-tubular boiler, and that no deficiency of water would be necessary. Mr. Tonkes, p. 323, states that the theory has been before attempted to be maintained but in vain. I take this opportunity of relieving myself of two other worries about boilers. Why when a boiler bursts is it also said to collapse? Does a shell collapse ? Next, why cannot many boilers be constructed with a weakest part, so that they may be blown out in somecalculated and harmless direction?-M. P.

of mine, and being laughed at for a fool, a few months after I was greatly astonished to find a locomotive fitted with one, patented by a friend of his, and come ints general use for the fire-box end of locomotives. The sketch is something after it, a conglomeration of section and elevation that will be understood, I dare say. Iss afraid if I put it all down piecemeal our editor cannot find space. The idea was the same; and before tur Bourdon was very useful, as by using the top screw na could tell by the graduated scale A what you had got in your boiler; and it entirely did away with that brass funnel, and long lever, and spring balances as was in general used in Sharp and Roberts' engines. Especially there was a drawback in it that I could see, that was the action of the steam would corrode the cylinder and piston; as a palliative to that, to some extent, there was a thumb-and-finger piece at the bottom, B, by which the driver or stoker could lift the piston occasionally to see that it as free. But Bourdon's beat it, and it will be some time before you find a better, if ever. -JACK OF ALL TRADES.

[5961.]-POWER TRANSMITTED BY DRIVING WHEEL.-The principle on which this is done is by means of the friction between the two surfaces in cottact. This friction, like unto all other frictions, is nearly constant for the same substance, and can be represented by a coefficient, say, 0:28 for iron pulleys, and 047 for

wood ones.

The total amount of this friction will depend on the force employed in straining the belt over the pulley by which the resistance is to be overcome. It also depends on the unity are of contact with the pulley over which it has to run. If A represent the unity are tension on leading side of belt, t the smallest tension on of contact, O the coefficient of friction, T the greatest following side necessary for the belt to have while in motion, and F the force required to draw the two ends of belts together before fastening, such that T and t may be sufficient to overcome the given resistance = B Tt. But as T+ t is constant at all velocities, as well as when the belt is at rest, we shall in consequence T + t find that F = both legs being equally strained 2 1 when the belt is at rest; therefore, equal to the force required in joining the two ends. From R = T—t, and

F=

T + t
"
2

we have T = F + R, and t = FE. Therefore T and t becomes known when F and Ris made 550 h.p. known R = , and F must be found from experi ment, or from the following table e cast-iron pulleys. When A 03 then F 19 R = 0·4,, = 0·5,,

= 0.6
= 0·7

= 1.5,

= 1.2,,

The smaller arcs being taken for open helts, the larger ones for cross belts. Having found F and R, T is also known, which is the greatest strain for which the cross section of the belt must be calculated to overcome the given resistance; that is, the cross sectional area of the

belt in 16ths of an inch must be equal to

Tin pounds Therefore, as 2 F or T + t is the force that tends to bend the shaft in direction of the belt, we cannot, in consequence, find the the sum of all the T+t's, or the sum of all the forces produced by any number of belts employed on the same shaft and between the same bearings, such that when reduced to one direction will be equal to the whole force, tending to bend or break the shaft in that direction. Consequently, the strength of the shaft must of necessity be greater than the sum of these forms. It is assumed that "Leather "knows how to calculate the strength of shafting sufficient to resist these kind of forces, as he only asks to know how many belts he can employ on any given shaft-which is sufficiently indicated in the above simple formula, deduced from many years' experience.-R. D.

[5977.]-STILL.-Believing it impossible that I could be totally wrong if I relied on the dicta of extensive advertisements confidently worded and never publicly contradicted, I adapted bits of vulcanized india-rubber tube instead of solder joints or screw unions for the many connections, &c., of in. steam-pipe into various vessels in a chemical manufactory. As soon as the steam was turned on there arose an ominous sulphurous fume from each of these conveniently flexible and yet perfectly air-tight unions. On visiting them with some anxiety at the end of the day, I found them all flabby, because most of their sulphur had evaporated, leaving the india-rubber as soft as it naturally is at boiling heat. On inspection a few days after I found them inelastic, cracked, and rotten, and was glad to clear away the discreditable remnants and revert to any other mode of connection. I have used valcanized rubber for parts of heating apparatus in many other ways, and I find that it is a total failure wherever its own cohesive strength and elasticity has to be relied on, but it serves well enough where it is merely required as packing with no great strain on it; also that its vulcanized and elastic nature lasts much longer under liquids, as water or acids (excepting always oil or grease), than in hot air, gases, or steam. Why should not "M." use the same material for the steam-pipes as for the condenser, and so avoid adding to the impurities which he will be sure to obtain? Pure water readily dissolves lead, therefore partially the lead in the composition pipe, but iron gas-pipe would be free from this objection. I know of a still (for water) in course of being fitted, in which it is considered sufficient merely to carry a jin. iron gas-pipe outside a house for 25ft. in order to condense 2 gallons in fourteen hours. When it is finished, if it succeeds, I will send more details if "M." desires.-W. P.

[5995.]-DIAGONAL STAFF.-I must leave this query to some other of your readers. I always use the pocket sextant or optic square, the latter instrument being a sextant fixed at 90. I would strongly advise Adagio" not to set out four main lines, as in surveying by angles with this instrument, which is at best a clumsy instrument.-F. H. SOMERVILLE.

[6010.]-WILKINSON'S PRINTING PRESS. In reply to "Vertumnus" (p. 335), what I mean by "get the bearers tapped" is this:-Drill a hole at the top of bearers (in the middle), and at the bottom in the same manner. Then make a thread to the thickness of screws, not particular what size of screws, if only they are made to fit well; these screws are to move the roller or cylinder to its proper position to suit the type. It is the mistake of the engraver only making two screws when I made four. Let the bottom screw be inserted in the same manner as the top one. Fig. 1 shows bearers, with

glue, with a drop of water to it; boil it till all is melted,
then pour it in the can. It would be better to buy the
rollers, furniture, and side-sticks.-ALFRED WILKINSON.
[6015.]-REMOVING GREASE SPOTS FROM BLUE
SILK DRESS.-To take grease spots out of silk take a
small piece of sponge or flannel, wet it with benzine, rub
the part well until nearly dry, stretch the part while
being rubbed.-C. AUBIN.

[6016.]-CREOSOTE.-It seems to me impossible to
Creosote wet timber, as mentioned by E. P. Saxon. I
tractors to creosote andried Scotch fir and larch with
have observed upon railway works an attempt by con-
portable tanks and machinery, but in no instance has
the penetration exceeded about fin. The practice some
few years ago upon public works in creosoting was in
the first place to effectually dry the wet timber in long
chambers heated from underneath, and when thoroughly
dried, placed within the creosoting tank, and the air well
pumped from the interior, which operation withdraws
the greater part of the air from within the pores of the
timber. At this point the creosote is turned into the
tank, when it penetrates to the very heart of the tim-
ber so effectually that when a piece of it is cross-cut it
presents the same shade of brown from outside to inte-
rior. The time occupied in creosoting twenty loads of
Memel would entirely depend upon the capacity of dry-
ing stove and creosoting tauka.-W. R.

Now cut out those pic

a quantity of leather scraps in the same until all of a glow; keep an iron plate over it, then put in the piece of steel that is to be hardened; urge the bellows gently take out and put over the fire until dry. My losses until the steel is pale red, then plunge it in cold water; through breakages were very serious until I tried the above, and none since.-C. AUBIN.

[6061.]-MAGIC LANTERN.-"Shopmate" will not require to tone or intensify his dry-plate transparencies, if taken on collodio-albumen plates, and developed slowly with gallic acid. I have always found the tone of does not show so well, as the high lights are likely to the pictures very excellent. A picture, if very dense, parencies. My skies are absolutely clear glass; they suffer. They cannot be too clear for lantern transshow no trace of deposit.-GEO. Fox.

[6061.]-DOOR-PLATE ENGRAVING.-The simplest method for filling in the wax of door-plates is to heat the plate sufficient to melt the wax, which must be done over each letter/separately, and is called priming. Then with a lighted candle drop in wax sufficient to fill each letter; and to make it level, heat the poker, and before applying take care that there are no scales; if there are any, ruh them off with an old file. You should only apply it at blood-heat, so that the wax may not be burned. When cool, take pumice-stone and water, and rub off all superfluous wax; afterwards rub all scratches out with coat rolled a cylindrical shape, and sewn to keep it water-of-Ayr stone, and polish with an old collar of a round, with rotten-stone and olive oil; and to finish, when all the oil is removed, rub the wax perfectly clean with a dry rag; place the plate across two pieces of wood, and with a length of a newspaper rolled round and lighted, apply the heat to the back of plate gently. You will see the wax becoming gradually bright; but take care not to apply it too long, or the wax will boil out of letters.-VIE.

[6066.]-HEATING BY HOT WATER.-" Alpha does not give the size of supply-cistern, nor does he state whether the pipes communicate directly with it, or if it is placed above them. In either case it should be filled well up while working, and then (if all is right) will not require filling again for a length of time. The best place for feed-cistern is directly above the boiler. It should be placed above the highest point of the pipes. In the latter there ought to be a small air-pipe. The stoker should not allow it to get empty enough to hold two or three buckets of water while working. I recom mend "Alpha" to see that it is well filled, and to have a good fire kept up; then if the pipes are not above 150 degrees, there is something wrong. And it may be-first, improper fixing; secondly, insufficient boiler power; or, thirdly, bad stoking. This latter is often the case, other hand, there may not be sufficient piping to heat as half fires will not heat the best apparatus. On the the quantity of air contained in the church, with the piping at 200 degrees, which will be about the limit.UN JARDINIER.

the seeds of the Paullinia sorbilis, order Sapindaceae, is
[6068.]-GUARANA.-"Guarana-bread, a product of
used in Brazil, both as food and medicine. The rolls
made from the seeds are powdered, and made into a
paste with water; or grated by means of the tongue of a
From Wylde's "Circle
fish, and sweetened before use."
of the Sciences," Vol. II., p. 636. "Guaranine, a supposed
alkaloid obtained from guarano, or Paullinia sorbilis."
Ogilvie's "Comp. Eng. Dictionary."-DERRY.

[6017.]-SALT SEA SAND.-" Tidal Works" will find that nothing better than sharp sea-sand can be used for concrete from cement and shingle, and I am unaware of salt water being objectionable for mixing the concrete. Indeed, many hydraulic engineers consider sea water preferable to fresh water, and accordingly use it, believ: ing that stronger work results from its employment. may, mention, moreover, that some strongly object to salt water for preparing mortar in engineering operations, as witness the specifications of some of the East Indian railways, where brackish water is strictly forbidden to be used, but why, I never could learn." Let me add one more word, that in house building, neither sea sand, unless well washed in fresh water, nor salt water must be permitted in preparing mortar, as walls built from such would nearly always be damp' owing to the hygroscopic affinity of the salt contained in sea water.-W. R. [6031.]-LANTERN SLIDES.-In reply to query I am happy to give "Saxon " information respecting the production of diaphanie lantern transparancies, which when properly prepared are very effective with a good solar lamp, and moreover exceedingly inexpensive. Sheets of some of the subjects most suitable may be procured from Barnard & Son, Oxford-street, containing twenty and twenty-five pictures. The articles required will be, first, squares of thin sheet glass, size 34in.; a roller-Í find nothing better than a ribbon roller covered with flannel; transferring varnish, and one small flat camelhair brush. The price charged for the transferring varnish is high, but it can readily be made in every respect equal to any you can procure. Place in a small gallipot some white rosin and apply heat gently until melted; then add, little by little, spirits of turpentine, stirring it all the while; it should, when cold, be of the consistency and colour of golden syrup; it should be kept in a wide-necked bottle. tures you may wish to mount from the sheet; lay one down, the plain side uppermost, on a sheet of paper, and damp it with a sponge; turn it up, and apply the transferring varnish in good quantity with the flat brush; [6070.]-ELECTRIC ENGINE.-The magnet that I place it on the glass, previously well cleaned, cover it with a piece of thin paper well damped, and with the put to one of the engines that I made was 4in. long from roller remove the superfluous varnish and air bubbles, the poles to the bend; but "Andrew" need not be parif any; prepare as many as you require, and put them by ticular as to size unless he requires it so. The wire was to harden for at least two or three days. Now remove about 19 gauge; the brake can be formed by filing two the paper on which the picture is printed with gentle hollows in spindle; he can get the proper place for the rubbing with a wet finger, or what I have found most armature by having it to be movable, and a small set excellent,'one of the indin-rubber sponges, very carefully screw, then he can set it to the required place. The towards the end, or the film of colour may be damaged, spindle did run in magnet, a small hole centred for the especially in the high light of snow-pieces (the more purpose; but it would look better to isolate it by a pillar. however of the paper you can remove the clearer will be The battery that I used is a carbon and zinc cylinder, the picture); dry the surface, and give it a thin coat of one pint, but one larger has better effect; one cell is size, nothing better than very thin Russian glue. To sufficient. I am sorry that I forgot the proper position protect the picture, and give it great transparency, for the armature and brake; but he will have very little place a bit of Canada balsam, from which the volatile difficulty in getting that right. If he will publish portion has been nearly all driven off with heat, on the his address in the Sale Column, I will send him more plate; cover it with a second square of glass cut the particulars, and will send a sketch, editor kindly persame size, and press in contact while heat is gently ap-mitting, of one to work with arm and crank, same as plied until the balsam spreads over the surface to the direct acting vertical steam engine.-J. MoSELEY. edges, keeping it pressed until quite cold. The picture [6075.]-LIFTING BOILER. -Case 1, 15 63 tons; is imperishable and as clear as any hand-painted slide, case 2, 9.21 tons.-FUM CHOO. and will well repay the little trouble of preparation.[6075.]-LIFTING BOILER.-The chains AB, BC will receive 9 tons strain each, and AD, DC, 15 tons each. [6039.]-CENTRE OF GRAVITY OF A SEMI--R. H. ELLIPSE.-I submit that "J. K. P." cannot possibly have proved (either in the ENGLISH MECHANIC for Nov. 6, 1869, or anywhere), that the centre of gravity of a quadrantal surface is where he places it (p. 381), namely at 6 of the radius from the centre, or, 65 from screws and bosses. The chase is to screw to the iron either base. He should bear in mind the beautiful and cast table; the table must be pretty true. The tympan round any line, the solidity of the solid of revolution simple theorem that when any plane figure revolves is fast to the chase, and the chase to the table. The tympan-frame is made of a piece of iron fin. thick and equals the figure's area the path of its centre of Jin. wide, and made to fit on top of chase. It is covered gravity. His quadrant generates a hemisphere, whose with best cotton, and the pins are placed in the cotton content is of the circumscribing cylinder, by "Euclid." to hold the sheet. What I mean by the tapes:-The Hence it equals a cylinder whose radius is of A B, middle tape is to be fastened to one end of the table, and and this would have the centre of its generating rect the two outside ones to the other. The tapes are to angle at half the above distance from A J, namely turn the table in and out. Fig. 2 shows tapes, &c. =40825 A B ; and if F be the centre of gravity of The finer the cotton the better it will work; cover both sides of the tympan. The bevelled woods are side- the short semi-ellipse, A F = 40825 A B, while if L be sticks-which it would be better to buy, it would only that of the long semi-ellipse, A L = 40825 A J. His cost a trifle-and the little bevelled woods are "quoins," whick are to hammer up to the narrowest end of the multiplier or 425 must therefore be 40825; and in side-sticks to make the type lift. Fig. 3 shows chase, furniture, side-sticks, type, and quoins. The type is to the quadrant, A E, instead of being 6 of A D, is } = be inked by a composition roller, made as follows:-Get a piece of bar iron, fiu. diameter, 16in. long, beaten out 5773503, about 2 A D.-E. L. G. out at each end so as to drill a hole through for the roller end to run in; and also drill a hole in the middle the hole and fasten the handle on. Then bend 3in. down at each end of the bar; make a wooden roller, 9in. long and 2in. diameter, with an axle standing in. out at each end; then cover the roller-stock with composition in. thick. You must fix your roller-stock in a can 3in. diameter exact in the middle, with a bottom to it; then make woods to fit the ends to hold it in the middle of the can. Fig. 4 shows the roller. The composition is made of treacle and glue: lb. of treacle to a pound of

FIG.I

FIC.3

COMPOSITION

GEO. FOX.

17

15

the northern lights I ever
[6079.]-THE AURORA.-One of the best displays of
saw was about 8 o'clock
was about 700 miles west by north of the Lizard; but I
one morning, the sky being quite cloudless, but then I
think they are seldom seen in this country in the
morning.-AROMA.

[6082.]-SEAMS OF MODEL BOILER.-What does

T. Barlow mean by 15lb. to the sheet? What size is the sheet? I will then answer him.-FUM CHOO.

[6082.]-SEAMS OF MODEL BOILER.-If you have

not had any experience in copper, do not attempt to braze it, but lap and rivet, tinning the lap and wiping before riveting; make hot afterwards and sweat the joints. I do not understand your 15lb. to the sheet; what does it weigh per square foot? I may be able to judge of the gauge; and for pressure, what class of boiler?-JACK OF ALL TRADES.

[6086.]-SIMPLE ASTRONOMICAL TELESCOPE.following such an absurd notion as the telescope he deI should advise J. M. Elphee not to waste his time in scribes on page 360. Whoever Professor Perkins may be, it is certain his idea is not based upon practical experience with telescopes, or he could never have suggested such an impracticable myth as a reflector produced by a revolving vessel of mercury. Even admitvature, what motive power could be devised that would rotate the vessel with sufficient regularity to retain precisely the same focus for any given time? Or how could the vessel be constructed, or the fluid so con trolled, that no ring-like waves would form on the surface during motion? Again, how would the professor overcome the inevitable law of instability WHILE HARDENING.-Carbonize [6043.] PREVENTING STEEL FROM SPLITTING which is common to all fluids, and which is appa fire by burning rent (even to the unassisted eye) in any pool of

of the iron for a handle. Then put a screw through his magic lantern. When the lime-light is used this is ting that the surface so produced is of a parabolic cur

[6040.]-MAGIC LANTERN.-Joseph J. Hartley will find it necessary to place a reflector behind the lamp of not necessary. The best reflectors are made of silvered Copper (Sheffield plate). Tin plate would do for a time, but is very inferior to the polish which can be obtained on the silver surface. The diameter may be rather greater than the lens. The light should be in the focus of the reflector.-GEO. Fox.

the

wid find a constant number is supplied for each machine [6106.]-BIRAM'S ANEMOMETER.-"Omicron and all particulars as to how many revolutions go to a hundred feet. The number of feet per minute the air is moving at divided by 88 will equal the number miles per hour.-FUM CHOO.

[6107.)-HARDENING WROUGHT-IRON. - Take pound them in a mortar to fine dust; or take leather some bones; burn them, until black, over the fire, the scraps, or tops of old boots or shoes, burn them into an iron box, put a layer of the powder an in above, and pound in a mortar to fine powder. Ars articles you may want to harden (large and small), p thick on the bottom of box; put the articles on, thes cover them fup an inch thick with the powder. Pat a cover on the top; place them in a good fire, until the have seen opened had no magnets, but the needle, it out of the fire; take the articles out quick, and [6095.]-MODEL TELEGRAPH.-The instrument I box is red-hot. In twenty or thirty minutes after, tabs which must be magnetic, is governed by a coil of insu- plunge them in water. If you want to mackle them, s lated wire, allowing plenty of room for its osc il-gun-lock plates, let them feel the air a few seconds, sed lations. The wire is wound parallel with the needle, when taken out of the water put them over the fre not in the direction that string is wound upon a stick. until dry; they will be as hard as steel. The above is ROBINSON CRUSOE. a far better plan than prussiate of potash. The mare the articles are finished before hardening, the better they look after, and easier to polish up again. AUBIN.

water, however still, that is exposed to the open air? side. The pivoting shoulder centres with slot for reAnd if the slightest vibrations of the air are sufficient ducing pivots with file, to one end of which is placed a to produce this, by what mechanical means will he pro- pallet guard to prevent file catching pallet while reducduce a revolving vessel which shall have less vibration ing, &c. He will require screw fernel for all those than the air itself? Yet this brilliant idea is expected kind of jobs. If he wants to put a pivot into a pinion to settle the question "whether the moon is inhabited." he should make and fit a drill to one of brass centres The learned professor might possibly be able to see and centre his pinion nut on his fernel, &c., and keep "the man in the moon," and if he saw him shed- moderate pressure of drill against pinion until drilled ding big tears of repentance for his past sins, his tele- deep enough, then file a nicely tempered piece of steel scope would be a "decided hit," but any further than so that it will go moderately tight into the pinion, cut this be may rest satisfied he will never get. This tele-off, give a tap or two with a hammer, and hammer it scope (very naturally) could only be used for zenith observations; the professor, however, nothing daunted, stump with hollow drill, put in brass stopping. Take on centre, &c. If a verge cock pivot, drill out old gets over (does he ?) this difficulty by using a large plane the centre exactly, drill hole, put in pivot, precisely the reflector. Of course, there is no trouble in making such same as for pinion. Trusting this will meet his views. a reflector, and the usual difficulties of working a large SHEGOG. plane surface perfect enough to supply rays which will bear sufficient magnifying to show the inhabitants of the moon, are as nothing to the enterprising spirit of the learned professor. The whole affair is too ridiculous to bear one minute's consideration, and like a host of other ideas which crop up from time to time about perpetual motion and such like, which venture to astonish the world with a new fact, they somehow or other mostly die a remarkably sudden death, not even a groan being heard. I am afraid this will be the sad fate of "The new astronomical telescope."-W. PURKISS. [6088.]-DRAWING GOLD AND SILVER WIRE."Standard" must take his ingots of gold or silver to & rolling mill, and have them rolled down to the size, that is, to allow for the drawing down; they must then be slit into strips (same mill) sufficiently thick; then well annealed at the mill, afterwards pickled in dilute sulphuric acid to clean the strips; then point them to enter the happy to give any further information our correspondent into halls, and burnt for an hour or two in a pipe-clay draw-plate, not drawing them too sudden at first. He should have a graduated plate; one of Shakespeare's will be the best. Use beeswax and lard oil melted together.

-J. MOSELEY.

[GO88.]-DRAWING GOLD AND SILVER WIRE.-If "Standard" is in the trade he can find a dead smooth file I dare say. Let him put it in a sheet iron box or piece of gas or water pipe-such as is used to convey water off the house I use for such purposes-with a ball or two of whiting; subject it to a red heat for a couple of hours, when cold clean both faces and file or grind them up; then take his conical triangular pump-drill and pierce the plate every in, with holes, so that the point just shows through; then with a scriber point burnish from both sides, letting it projectdifferent lengths through the plate will have holes in it different sizes if made properly, one a shade larger than the other. I have drawn iron, steel, copper, brass, and silver as fine as the hair of my head wit a plate prepared by these means. Get some dross black, which is the finest ivory black; make into a paint with stale beer; warm the plate, brush into the holes and all over the plate; use the tube as a muffle without the whiting; put it into the fire, get all to a nice red heat; and harden end on in clean water; it is fit for use after polishing the holes out with powdered pumice and box or dog wood, or powdered Turkey stone; use strong soap solution for lubrication while drawing, Soften your ingot; hammer out, or hammer flat, and cut in strips according to the length you want the wire. I have an acquaintance, a wire-drawer of gold and silver wire; his holes are all jewelled for the finest work, and I was informed that it could not be done in steel plates. I have tried my hand in the above, but gold does not fall to my share, and have succeeded in doing the impossible once again. You can draw it as hard as you like. If you want any length, you will want a drum to wind it upon; what little I have wanted I have pulled through with the pliers some five and six yards long.-JACK OF

ALL TRADES.

[6090.]-MAGIC LANTERN.-I am not clear about "Sol's" failure. If the outlines had not been perfectly dry, they would have worked up and mingled with the colour when the latter was laid. Perhaps the colouring was humid when the varnishing was performed, in which case the whole would be disturbed. But why varnish? It is unnecessary in comicalities, and indeed ought to be used very sparingly. Experience has taught me that pictures of high and delicate finish are more or less deteriorated by being varnished all over. The tints may and ought to be kept sufficiently pure and transparent without this barbarous practice. I varnish very seldom, and only when I desire great transparency on broad surfaces exposed to high light; before doing this, I subject the picture to heat for three or four hours, and when cold the operation of "lighting up" is performed with a sable pencil (Fig. 4, p 338, No. 301), very lightly and thinly, and only on those parts requiring the "effect." This is one of those finishing touches of the experienced eye and hand, not much in itself, but every. the Outlines," p. 838. May I ask that all queries on this subject intended for me, be headed "TO SABLE"? [6098.)-STRAIGHTENING SAW.-Let "Builder" take the blade out of the back, which may be done by placing it between two pieces of wood in his bench screw, and knocking the back with a piece of hard wood from the end that comes up to the wood handle. After the back is removed, take the blade, and see where the buckle is in the front; it wants hammering upon back of blade upon a smooth flat iron or anvil, with a smooth-faced

thing in the doing and the effect. See on "Hardening

[6095.]-MODEL TELEGRAPH.-To give a descrip-
tion of the simplest telegraph instrument in use, so as
to enable a "Constant Subscriber" to make one, to-
probably occupy a page or more of the MECHANIC. I
gether with the drawings absolutely necessary, would
tricity," price 38. 6d. (perhaps the cheapest book ever
would strongly advise him to get Ferguson's "Elec-
published), where he will find the most complete in-
structions he could wish. I have myself lately made a
pair of full sized single needle instruments, and shall be
are fitted for actual work, but model or toy-instruments,
may require. The cost of the two was about 15s. They
such as are sold in the shops, could easily be put to-
gether for less than half.-GLAUPHUS.
discourage "Battery," but fear he will not find his
[6096.)-WOLLASTON BATTERY.-I do not wish to
for.
namesake as great a success as he, perhaps, has wished
Wollaston's battery was a valuable piece of apparatus,
Before other improved forms were invented
but has now fallen almost entirely into disuse, owing,
chiefly, to its low power and want of constancy. The
current obtained from the six cells mentioned would,
probably, be much less than could be got from one small
Bunsen cell, costing about four shillings; and the
degree of power would rapidly decline, and after a short
time entirely cease, while the Bunsen would continue
its primitive energy for many hours. If the plates are
taken out of the acid when not in actual use it will last
for days, or even weeks, without its power being quite
exhausted; and, at the last, will probably give greater
signs of electrical action than six Wollaston cells after
two or three hours' work. Twelve cells might, perhaps,
produce a small spark between charcoal points, but, I
should think, to get anything like an electric light, at least
a hundred such cells would be required. This is mere
would not give a greater light than ten or twelve
guess-work of course, but I should think that number
elements of the other form of battery mentioned. The
number of alternations of zinc and copper plates with
which Sir Humphrey Davy originally produced the
electric light was two thousand.
would work a coil, effect metallic deposition, induce
"Battery's "six cells
magnetism in soft iron, ring bells, work telegraphs, and
perform many experiments requiring but small power;
but I would advise him not to waste his time and money
(as most of us do) the most he can get for his money, he
on a second series of the same kind, as if he requires
cannot fail to be sadly disappointed with the result.-
GLAUPHUS.

on this subject, if he will look back he will find that I
[6098.]-LEAD BURNING.-In answer to G. Howarth
illustration of apparatus, in No. 295, query 4822, p. 211.
gave the same information that he now requires, with
RosKELL.
It is the method employed at vitriol works.-J.

[6100.]-IMPROVEMENTS IN PIANOFORTES.-In
reply to Mr. J. Jenkenson-who I am glad to hear from
Again-I believe the third string in pianofortes has
unisons; the former was patented by Kirkman. The
been made both half and double the length of the
effect is increased brilliancy, something like the effect
of a rather weak principal, in combination with two
open diapason ranks. Of course, a sub-octave string
would induce a very full quality of tone, if well carried
out, but I fear it would lack brilliancy. I think it would
be well worth trying in the high trebles, for the vibra-
tions would not be so short.
Jenkenson's plan for placing the unisonous treble strings
The more I think of J.
of them side by side-the better I like it. Will he oblige
of pianos in continuation-indeed, of placing four
by telling me if he has carried out his design, and the
result? Since the above was written it has occurred to
sonous strings, say, at one eighth of their length from
me that when the same hammer strikes the two uni-
the bridge, it must strike the super-octave string at only
one-fourth its length from the bridge, so its tone cannot
be much to boast of in the way of brilliancy. I re-
further up the compass than C above the staff, i.c., an
member Kirkman did not earry his super-octave string
octave below the then compass of his instruments. The
string at only half the usual distance from the bridge,
super-octave string struck at one-fourth. Perhaps
would not, I think, be so offensive as in the case of the
striking near the bridge might cause less loss of bril-
liancy.-THE HARMONIOUS BLACKSMITH.

to this query will be found among the letters.
[6113.]-LATHE-HEADS.-A reply from " J. K. P."

made it years ago, from a recipe in an old work, of wh
[6114.] DISSOLVING WATER-COLOURS.-The
Chinese or Spanish white, so-called, if made as I have
ing, finely washed, and burnt alum, equal parts, made
up again without grinding, for it sets like a stone. Fis
crucible, when once set, whether mixed with gum arab,
white is the freest working, but that wants well washing
parchment size, sugar candy, or glair,is difficult to w
verditure, Scheele's green, all want serving the same.—
and digesting in hot water before tempering it for water.
colours, tojfree it from the salts. Red lead, vermilio,
JACK OF ALL TRADES.

in error in supposing that electricity, in passing thronga
a coil, increases in quantity as well as intensity. Such a
[6115.]-ELECTRICAL.-"American Subscriber" is
drawing plate increases in length almost indefinitely;
not the case, the quantity decreases as the intensity i
creases. A wire drawn through a smaller hole in a
but it cannot, strictly speaking, be said to increase in
thickness. On the contrary, it diminishes in proportion
perfectly analogous to a current of intensity, small is
to the length to which it is drawn. This I take to be
current of quantity of comparatively low intensity, the
length of wire standing for intensity, and the thic
quantity, being derived by inductions from a primary
wire of the first coil would, therefore, in all probability,
be too small in quantity, whatever its intensity might
for quantity. The current proceeding from the secondary
be, to work the second coil at all, as the primary wire
wire of the first coil. Supposing the first coil to be the
circulating through it precisely the same as the primary
of the second coil would require a primary current
much larger and more powerful of the two, the quantity
of electricity given off by it might be sufficient to inacce
magnetism enough to work the second coil, but I don't
make the contact-breaker of the second coil work, for the
it. Besides which it would be next to impossible to
current, from its intensity, instead of being broken the
instant the platinum screw left the other part of the
brake, would continue to pass in a stream of sparks irod
Since writing the above I have experimented with A
one portion of the contact-breaker to the other. P.S.

Bunsen's cell and

two coils. The results are in ceptible, though the first coil was in powerful action.secondary wire of the second coil whatever was per accordance with what I have stated. No effect on the

GLAUPHUS.

[6116.]-CISTERN.-I was wrong in the reason given for the smaller flow through the longer pipe, as r yield less than the short one. Were there no friction, Grenfell observes; though right in the fact that it will both would yield equal flows, the head of water being reckoned, as he says, from their feet, not their tops. Thanks for his useful experiments.-E. L. G.

Merri, I think the time to fatten poultry at the least [6122.-POULTRY BREEDING. In reply to Mr. cost (or, rather, with the greatest profit; for spending 1s. to obtain 2s. is better than spending 9d. to obtain 18.) is to commence feeding teen days for "fattening," they will be ready for sale generously" when they are about three months old, so that allowing ten or fourmonths, that in September will not sell for more than when between five and six months old. Birds of twelve 5s. by Christmas time-fowls have been sold in London 1s. ed., by judicious feeding may be made worth 48. or able to buy or to breed will depend on the cost of feet. this season at from 8s. to 6s. Whether it is more protiting and fattening for market; if the value of say bourhood is only slightly less than the cost of 20 birds eggs and the food for 20 chickens in Mr. Merri's neighsix months old, it is obvious that, taking into account the losses by death and the trouble of looking after the chickens, buying would be more profitable than breedand fourth questions, the dark-coloured fowl with A ing. This would be especially the case if Mr. Merri can one to breed from himself. With regard to his third Fleche, a French breed; a bird somewhat similar is the comb in the shape of two horns is most probably La Creve Coeur, with a small two-horned comb, a tuft not given to ramblin, and very tame; but the form on the head, and a cravat of feathers under the neck. is the more stylish fowl, standing higher on the leg, and Both of these are large, fleshy birds, easily fattened, with a brilliant metallic lustre en the plumage of the male, who should weigh about 71b. The chickens are hardy, and make excellent table birds, but cooks are pretend to say what his other hen may be, unless it prejudiced against their dark-coloured legs. I cannot a Dorking: the presence of five toes will settle that point. The Shanghae, or Cocl in China, is divided into three principal classes-the tuff, partridge, and g (alias Brahmin Pootra). Their chief characteristics a looking thighs, and feathers down the legs; the comb the absence of anything worthy the name of tail, beavyerect and evenly serrated, except in the grey class, where it is sometimes of the simple form, at others

the centre of buckle, in this wise: one blow outside edge, hammer, commencing from the back, in a line with defect of tone, resulting from striking a sub-octave buy fowls bred from a good stock and has only a common then so that the blows may fall in a triangle then one, two, a little farther in; then one, two, three, a little farther; and by taking particular notice of the effects of each blow you will very soon find out where to expend your labour to the greatest advantage to obtain your end. Do not hurry, but take it quietly, and put your considering cap on. It is a thing that has puzzled a great many, but nothing is easier, with a few effective blows well directed. But one in the wrong place, and you may put four cross buckles where there was only one; then you get sorely puzzled; you get out of temper: you hit at random, and your saw is spoiled.-livered on naturel, it does not curdle soap and block up JACK OF ALL TRADES. [6094.] - SWISS

PIVOTING TURNS "Young Jobber will find his query beautifully answered (5805), by Tometer." In the general use of turns he has eight centres, viz., one pair brass, one pair conical female, with reversed ends, for shortening pivots, etc.; one pair male and female; and one pair pivoting ditto. The conical females for the convenience of balance wheel work, turning down collets of verges, staffs, pinions,

unable to state what chemical ingredients are employed
[6105.]-CLARK'S (SOFTENING PROCESS.-I am
in Clark's softening process, but Professor Frankland
continues to show its excellent effect as applied to his
own domestic supply from the Grand Junction Com-
pany. "The water so purified," he says, "is bright,
sparkling, and pleasant to the taste; unlike that de
the pores of the skin with an unctuous and dirty solid
when it is used for personal ablution." There appears
to be no reason, except that of the slight expense in
volved, why the whole of the metropolitan supply should
not be purified by this process before delivery to con
Canterbury, Tring, Caterham, and other places, suffices
sumers; and its succesful working on a large scale at
to show its entire practicability. The aggregate saving
in washing items from the use of soft water-as exempli- triple-folded or pea-comb,

The Spanish breed bas

etc., generally used with one of brass centres at the left lied at Glasgow would be something enormous. P. F. uniform glossy black plumage, with largely-developed

[6125.]-DEXTRINE.-Dextrine is prepared as follows:-Make a thick paste by boiling potato starch with water. Put this into a capsule, stir in a few drops of H SO; the thick paste will soon become a thin liquid. Place the capsule in a water bath over a Bunsen burner. Keep the mixture in the bath boiling until the mixture in the capsule becomes transparent. The mixture itself must be made to boil. When the liquid becomes clear chalk is to be added cautiously, until the mixture ceases to be acid to the blue litmus paper; it is then to be removed from the burner; the lime sulphate is to be filtered out; the liquor is then to be put in a place to dry up; the residue is a glassy solid, not soluble in alcohol. If the solution of dextrine in H2 SO, is made to boil it is converted into sugar starch. Dextrine is the principal ingredient of British gum.-F. GRAYLING. [6126.]—SPLITTING PRINTS.-I presume that the methods of splitting a £5 note, and of removing an en. everything he could wish to know upon the subject. found upon the plate of copper there was nothing more

[6168.]-PERCUSSION SIGNALS.-These were in--DELTA.
vented by one of the sons of the late Professor Cowper,
of King's College, London, and consist merely of a
small round tinbox with some gunpowder and a small
piece of the stuff that fusees are tipped with inside;
a strip of sheet lead about in. wide is soldered to one
side of the box, and by bending this round the rail the
box is held in its place till a wheel passing over it arrested my attention.
Imme-
explodes it. I will not answer for their being made
Professor's hands, and saw tried during my pupilage,
exactly thus nowadays; but those that I saw in the
were so arranged. I should hardly call them "per-
cussion," and I know nothing about their cost.-J. K. P.

as I have attended to every direction and bit of instruction given to others in your columns, that is as far as I am aware; yet it will not act at all. It is constructed as follows:-Into a very large pot-a common preserve pot-is inserted a sheet of common zinc, amalgamated, the surface exposed to the acid is 4in. x 12in. in area. Within this is placed "a common flower-pot to serve as a porous cell," I am certain it is quite perous too; within this a rod of gas carbon 5in. long by 2in. square. Outside the porous cell, in contact with the zinc, I placed sulphuric acid diluted with eight times its bulk of water; inside the porous cell I put nitric acid diluted with about six times its bulk of water. With this arrangement I could feel nothing whatever when contact was made, without wires, with the tongue and lips. When the circuit of a pile, made with only six pieces of zinc with as many pieces of carbon and cloth, was com pleted by the tongue and lips it was almost unbearable. The zinc was 2in. square, and excited with common salt and water only. If any one could kindly explain the cause of failure they would greatly oblige-ROBINSON CRUSOE.

[6195.]-CUTTING MILLBOARDS FOR BOOKBINDING.-Would "Ab Initio" kindly inform me the way the boards are cut for books with such smooth square edges, as all I get are so hard and gritty they take the edge off of everything used about them; and what they may be cut with by an amateur ?-ROBINSON CRUSOE. [6196.]-CASTING LEAD PUMP-BARRELS.-Will "Practical Plumber," or J. B. Primus, inform me how lead pump-barrels are cast or moulded, and the square cistern-heads and spouts, i.e., what is the core of the barrel composed of? as it seems to me, if it is a solid iron core and the lead will shrink on cooling, it must require considerable force to withdraw it from the barrel. -GUSTAVA KNOX.

[6197.]-CANDIED PEEL.-Will some subscriber inform me how the candied lemon and orange-peel is manufactured, such as sold in shops ?-GUSTAVA KNOX.

[6198.]-EQUAL BALANCING.-Does Mr. Malbon mean by "equal balancing" that in levering the engine round it should be as easy going up as down?-T. B. [6199.]-CEMENT FOR AMBER.-Would some correspondent kindly inform me of a cement that will stick firmly the broken amber mouthpiece of a pipe? I have tried "Diamond" cement, but it has failed.-ULSTER. [6200.]-MECHANICAL IMITATION OF THE ACTION OF THE MOUTH.-Can any of your readers tell me of any mechanical means to suck or draw up in imitation of the human mouth ?-T. WALTER.

[6201.]-PUNCHES.-Could any reader inform me how the steel punches are made to stamp the names and figures in iron and soft steel?-A BLACKSMITH. [6202.]-MILDEWED COTTON.-Can any reader kindly furnish me with a recipe for taking mildew out of yellow cotton without altering the colour?-LINUM.

[6203.]-SLEIGH.-Would some good friend give us a sketch, with dimensions, of a sleigh? Although, perhaps, too late for this season, I should like much to make one during the long days of next summer.-C. S.

[6204.]-BREWING.-There is a substance of which the name sounds like "foots." It is called also "green sugar," and is used in the making of some ales. Can any of your readers tell me what it is, and how it is made?-PERMIAN.

servers of 1869 differed from the Indian observers of 1868,
as to the corona ? What does the pola rization of its

light prove?—A LADY.
[6214.]-PEEP-SHOW.-Can any reader instruct me
how to construct a "peep-show" to amuse juveniles
pictures, say 15in. by 20in? I have a magie lantern lens
in.; can I utilize it? if not, what sort of a lens, where
can I get it, and what price ?-BOPEEP.

[6215.]-RIPPLES AND WAVES.-With the editor's
permission, would "E. L. G.," or any other corre-
spondent, favour me with some observations upon
ripples and waves-with what is new on the subject? I
should like the case of circular undulation caused by a
stone thrown into a pool to be gone into; why the
waves increase in amplitude and altitude as they spread.

-M. P.

[6216.]-SIZE OF ULTIMATE ATOMS.-Will Mr. Barwick, or any other correspondent, state upon what grounds Sir W. Thomson judged their size to be between the 100 and the 2,000 millionth of a centimetre? I can understand the maximum might be obtained, but not the minimum.-M. P.

[6217.]-DEFECTIVE HEATING APPARATUS.-I
had a small hot-water heating apparatus recently fitted
up, consisting of a 24in. saddle boiler and 86ft. 3in. pipe,
each flow and return at an elevation of 12in. above top
of boiler; the small supply cistern is fixed 24in. above
the top of boiler, and is connected to the boiler 2in.
above its bottom; when the water is heated it is forced
out through the cistern to the extent of several gallons.
Now what I wish to know is, has the flow sufficient ele-
vation for proper working; should the supply-pipe be
connected to return-pipe instead of boiler; would it be
an improvement to put on more pressure by connecting
the supply to a large cistern at a higher clevation;
should the air-cock on end of pipes be always left open?
An explanation from a kind correspondent will oblige an
-INTERESTED SUBSCRIBER.

[6218.]-COATING FOR MACINTOSH WRAPPERS,
&c.-Will any of your correspondents kindly give me a
good recipe for making an elastic varnish, impervious to
heat and moisture, of sufficient consistency to make a
good coating and to he dried quickly, with best mode of
1 think such as used for macintosh
applying it?
wrappers so generally will do.-FAZEBY.

(0219.]-TELESCOPE LENSES.-Will one of your
talented correspondents inform me whether a 3fin. Ó. G.
is likely to be of any use to an amateur only, when the
price is £3? An optician of good reputation asks £7 for
the same article. I am consequently undecided as to
buying the cheaper article.-CORNUBIA.

[6220.]-WATCHES.-Is a centre seconds watch in its complicated construction equal or greater in hazard as to continual motion and time-keeping properties, &c., as an ordinary lever watch of the same finish? N.B.Difference of price understood.-FANCY.

[6221.]-GAS FLAME DENUDED OF ITS IMPURITIES.-Would Mr. E. Ward Jackson, whose letter on this subject appears in No. 301, favour us with a descriptionand drawings ?-MAC.

[6222.]-DRAUGHT IN ENGINES.-We have two portable engines; one will draw well at all times, while in the other the fire will not draw up the tubes at all when the atmosphere is heavy, or the wind in a particular quarter, so that we cannot keep up steain. Will some one kindly tell me the cause, and how I can remedy [6205.] CASEING TOBACCO. Would "Inlandi?-MARTIN. Revenue Officer" kindly inform me if there are any Excise restrictions in caseing tobacco; in using in the liquor, salt, saltpetre, or lime; also is there any restriction as to the quantity of condition that tobacco is to be retailed with; also in making British cavendish? May it be made with sugar, treacle, or rum ?-BEN LODDY.

[6206.]-PIANOFORTE CONSTRUCTION.-Would "Musicus Vulci" be good enough to answer me the following questions ?-1st. Why is it that pianofortemakers give such a good price for "tea-lead?" I have myself sold it for £21 per ton. For what purpose do they use it? 2nd. Will the "H. B." tell me what sort of things they are that are usedifor warming the keys of pianos in winter? for I have been told that the cooler and drier the instrument is kept the better will be the tone; for I think if the "H. B." would consider well one day after he has done beating his "iron drum" (anvil) that he could make a pianoforte into a musical egg hatching machine, so that the dear little chicks could open the ball (egg) to the tune of "Lardy Dardy," "Up in a Balloon," or "Does your mother know you're out?" 3rd. Does the "H. B." believe in the glass insulators that are sold to put under the feet of pianofortes, to keep, I suppose, the sound from travelling along

the floor?-B. E. LODDY.

[6207.]-VULCANITE CHAINS.-Would any of your readers inform me of any method of blackening vulcanite chains ?-A. W. BROWN.

[6208.)-STAINING WALKING-STICK.-How can I stain a holly walking cane black; and what can I colour the polish black with ?-NIGER.

[6209.]-UNEQUAL STEAM PRESSURE.-I should be most happy to receive from "Leh Teb "the details of his very simple expansion gear, which requires neither wheels nor tappets. I am afraid the beam and connecting rod of our low-pressure engine would not be able to stand the strain of the whole weight being worked by the low-pressure cylinder.-INQUIRER.

[6210.]-PREVENTING SPINDLE HEATING.-Will any reader inform me what I can put on a spindle to keep it from heating ?-GUILLAUME.

[6211.]-DORMICE.-How are these, sold in this country, caught ?-SPHINX.

[6212.]-ODIC FORCE.-Would " Sigma" kindly inform me whether any experiments have been made on odic force since those of Reichenbach, and if so whether they tend to show the identity of odic force with magnetism? In" Sigma's" opinion, are the phenomena of table-moving satisfactorily explained by odic force; and what does he think of the French Academy's explanation of table-moving ?-A. C. G.

(6213.]-THE ECLIPSE. Will Mr. Proctor or "F.R.A.S." tell me in what respect the American ob

[6223.]-BUNSEN'S BATTERY.-Will any reader give an opinion of the following solution in the porous cell with the carbon:-28oz. soft water, 2oz. refined sulphuric acid, 2oz. bichromate of potash, and 31grs. of chromic acid?-M.

[6224.]-NITRATE OF SILVER.-How can I fuse the crystal into sticks?-M.

[6225.]-GREY BEER.-If a glass of grey beer is held
between a light and the eye it looks as bright as sherry,
but if you hold it so that the light is between you and
the beer it looks as thick as paste. What is the cause
of this phenomenon; and why in the first instance do
some beers turn grey? I hope some of our scientific
correspondents will be able to answer this, as I can find
no account of it in any book.-AROMA.

[6226.]-FIREBOX.-TO LEONARD TODD.-May I
ask Mr. Leonard Todd if he would kindly give a sketch
and interior dimensions of the firebox of his steam
boiler; how the tubes are fixed; and if angle-iron is
used in its construction? and description and sketch of
the friction-clutch gear for the driving-wheels will
Has Mr. L. Todd tried annular tubes, and
oblige.
with what result? A sketch of the arrangement of his
engines will be esteemed a favour.-C. T.

[6231.-MAGIC LANTERN.-1. Can the oxyhydro lime-light be used with only one gas bag; that i the oxygen; the hydrogen to be obtained from burner in the room? 2. If not, can a bag be filled på hydrogen from the gas-burner, before using, and th employ two bags ? 3. Must the jet be placed before t lime cylinder, that is, between the cylinder and e denser? Of course in all the above, I mean for the t gases to mix a few inches below the jet. 4 Is it the chamber where they mix inside he to place the lautern ?-LIME-LIGHT. [6232.]-OXYGEN IN WATER.-I am aptions to know something about the oxygen in water, its effects on the body, the effects of boiling the water and main it into beverages, &c. Perhaps our friend "Sig will oblige? You noticed a letter like this from me I have not seen it in the queries.-SAMUEL IEBOTION,

USEFUL AND SCIENTIFIC NOTES.

SUBMARINE TELEGRAPHS.-The progress story by submarine telegraphy during the past year has be The enormous length somewhat remarkable. 14,568 knots of cable was actually manufactured in and no less than 11,292 knots submerged. The pri lines laid were the British Indian; the British I Extension (Madras to Singapore and Penang 2 Falmouth, Gibraltar, and Malta; the Anglo-Mic ranean (Malta to Alexandria); the Marseilles, Al and Malta; the West India and Panama; the C Submarine; and sundry small ones in connectar a the Post-office, for which also a cable for incras the Irish accommodation is approaching completno s Silvertown. This is about the most massive ever mai, and contains seven conducting wires.

CHINESE WATERPROOFING

COMPOSITION –

Dr. Sherzer, an Austrian official at Pekin, sy
Eastern Budget, has just sent to his Government se
specimens of a Chinese composition called Sear
which has the property of making wood and other
stances perfectly water-tight. He says that he ask
in Pekin wooden chests which had been to St. Pe
burg, and had come back uninjured, and that t
Chinese use the composition also for covering dra
baskets, which are afterwards employed in car
oil for long distances. Cardboard, when covered
the composition, becomes as laid as wood; and 1
wooden buildings in Pekin have a coating of it. It
sists of three parts of blood deprived of its fibrine,
of lime, and a little alum.

Pattern Maker's Tools, 240.

5726

5733

Becquerel's Coloured Daguerreotype, 240.
Lamp, 240.

5734

Cricketing Bats, 243.

5788

Strength of Phantom Wheels, 240.

5742

Proportions of Steam Engine, 243

5747 Portable Canoe, 240.

5751

Casting Brass, 261.

5760

Slate, 261.

5761

Watch Dials, 261.

5775

Brazing Steel, 262.

[6227.] - GALVANIZED PIPES. In the Boston 5725
Journal of Chemistry is an article warning against the
use of "galvanized pipes." It states that ordinary pond
and spring-water attack the zinc almost immediately,
and remove it in the form of poisonous chloride of zinc,
&c. Can any one state a case of London water having
affected such pipes, and of injurious results therefrom?
-A. C. G.

[6228.]-GETTA-PERCHA FOR PIPES, Erc.-Will
somebody say from experience whether the lining of
cisterns with guttu-percha and the use of gutta-percha
pipes for the conveyance of drinking-water imparts a
taste or smell to same ?-A. C. G.

[6229.] WALKING-STICK CAMERA STAND.Could any reader tell me how I could make a cheap walking-stick camera stand? A rough sketch would oblige-C. HANEY.

[6280.]-MAKING BREAD.-From some cause or other, I cannot succeed in making bread in a new house into which I have recently removed, although I proceed in exactly the same manner as previously, and with similar materials. The house is damp and draughty. The yeast is prepared by a recipe which has hitherto never failed; the flour is from the same mill; but the dough will not rise. What should be the temperature of the room where the sponge is set to rise? I mix the yeast with water fresh from the well, which is quite soft. Can the fault be with the water? What sort of vessel should I set the sponge in ?-M. B.

5741 Patents, 240.

5787 Aluminium and its Alloys, 262.
5788 Rose-coloured Prominences on the Sun, 22
5789 The Inter-sidereal Ether, 262.
5796 Division of Ellipse into Equal Parts, 262.

5798 Violin Pegs, 262.

5803 Compasses in Iron Ships, 262
5810 Damp-proof Paper, 262.
5816 Soft Soap, 263.

5817

Water Wheel, 263.

5820

Glanders, 263.

5821

Casting, 263.

5824

Magnesium Light, 269.

5827

5829

Dissolving Silk in Cupro-Ammoniam, 263.
Iodine in Milk, 263.

3830 Harmonium, 268.

5888 Elementary Mathematics, 263.
5834 Harp Music, 203.
5887 To Millers, 263.

5838 Alarum Bedstead, 263.